SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '97ad40d624c69790433299df220443ee7711a3ed069b34b0725397b14aaf583c' 
  AND token = 'CNlH58qSaWUV9i38nUZHZPPf6ssgFNIBwRpCGDEung8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}